Colic. It's a grim word with dire meaning for horse owners. Colic kills backyard ponies and million-dollar race horses alike. The early symptoms can be subtle, easily missed. By the time the signs are unmistakable, sometimes it's too late.
Erin Venable, assistant professor of equine science at Southern Illinois University Carbondale and an expert in equine nutrition, wouldn't be the first researcher to want to find a cure. But she is one of a small number with access to one of the best research tools available – cannulated horses, eight of them.
A cannulated horse is one that has had a cecal cannulation procedure. That means the horse has a surgical portal through which researchers can access the section of the horse's gastro-intestinal tract called the cecum, which is the anterior portion of the large intestine, or the hindgut, which is where a horse does most of its digesting. The cecal cannulation makes it possible for SIU researchers to sample intestinal contents in order to study nutritional or digestive physiology.
Venable came to SIU after nine years as a nutritionist at Purina Animal Nutrition. She found that horse owners, regardless of their educational backgrounds and despite the wide range of horse care philosophies, were anxious to learn more about how to care for their horses. As she strove to answer difficult questions, Venable said she was continually frustrated by the limits of what is known about horses.
Colic is the leading cause of death in adult horses (after old age), according to a 1998 study by the U.S. Department of Agriculture. At that time, the colic cost horse owners an estimated $115 million a year. Another, more recent study, The Horse Report, prepared by the Center for Equine Health at the University of California Davis' School of Veterinary Medicine, stated that approximately 920,000 horses suffer a colic episode each year, with more than 64,000 of those life-threatening situations.
Despite these numbers, reliable prevention of colic and effective early treatment of it remain a mystery. Venable, who has devoted her career to solving problems, plans to use the SIU cannulated horses to address many equine issues. Many of those issues relate to colic. Efficient and reliable methods of colic prevention and recovery are her most ambitious goal.
“These cannulated horses allow us to study in real time what's going on in the cecum,” Venable said.
One thing she wants to know more about are the microorganisms in a living horse's functioning cecum. There are thousands of bacteria in a horse's hindgut that are not yet identified. A healthy bacterial profile is necessary for a horse to digest the fiber that composes most of its diet. To assist production of “good” bacteria, many horse owners add probiotics to their horses' diets. However, conclusive proof about the effectiveness of probiotics is lacking.
“We have thousands of bacteria that have never been identified in a horse's cecum, so it's no wonder probiotics don't work,” Venable said. “We are making recommendations for an animal's health and we don't even know what is really going on in the system.”
Real-time access to a horse's digestive system, provided by SIU's cannulated horses, will help Venable and graduate student researchers identify the profile of bacteria present and how that changes with diet, stress and travel. Ultimately, that will contribute to a better understanding about what a horse really needs to prevent, treat and recover from a colic episode.
Stephanie Bland, a doctoral student in equine science, is conducting research using samples from the cecum. She recently completed a two-part nutraceutical study in the laboratory in which she studied the effects of a dietary supplement to see if the supplement decreased the opportunistic bacteria in the hindgut. Now she's taking the study more directly to the horse to study several dosages, again looking to see the effects on opportunistic bacteria, but also testing the digestibility of the supplement.
“This is important because a majority of nutraceuticals (supplements, probiotics, etc.) do not have tested and approved dosages – only recommendations,” she said.
Other SIU equine research with the cannulated horses involves studying how horses' gastro-intestinal systems react to travel stress. Change in environment or diet can lead to colic in horses. Many horses are frequent road travelers. Venable describes the cecum as “the ultimate stress organ,” so it's reasonable to expect signs of stress to show up in the cecum.
Other projects may involve testing some of the theories of colic prevention – namely, that feeding should mimic a horse's mobile grazing pattern as much as possible. This means feeding a diet high in fiber and allowing a horse to eat many small meals a day. This is easier to do with some horse management systems than others. Venable said future research may get into the specifics of how to feed to prevent colic, particularly in stalled horses or those without free, continual access to pasture: how many meals a day, how large, and how long is the minimal daily turnout required for a horse with good gut health?
As for the horses themselves, Venable states quite plainly there are no horses better cared for than the cannulated horses at SIU – because of the students who take care of them. Venable had a team of nine undergraduate students in the college's “i2i” program to help care for the horses over the summer as they conducted research.
“They are heavily invested in these horses,” she said. “They've sat up all night with them, they've performed daily examinations, daily grooming and bathing, they make sure the horses get the pasture turn-out time they need. There's a huge amount of ownership and connection for the students and our cannulated horses.”
The horses are quarter horses or Thoroughbreds, selected because their body types are the most common for horses in America. The horses are all in the prime of their lives, five to 10 years old. Venable selected them based on overall health and temperament.
“These horses are all special to us,” Venable said. “Ultimately, they will save a lot of lives.”
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